scholarly journals New Evidence for Accretion Disks in AGNs

1989 ◽  
Vol 134 ◽  
pp. 245-250
Author(s):  
Jules P. Halpern ◽  
Kaiyou Chen
Keyword(s):  
Line Profile ◽  
Accretion Disks ◽  
Electron Scattering ◽  
Direct Evidence ◽  
Radio Galaxy ◽  
Narrow Range ◽  
Thin Disk ◽  
Line Profiles ◽  
New Evidence ◽  
Lines Of Evidence

We have refined our calculation of the line profile of a relativistic, Keplerian disk by incorporating a variety of emissivity laws, as well as broadening due to turbulence or electron scattering. The significant improvement in the fit to the double-peaked Ha line profile of the elliptical radio galaxy Arp 102B provides the most convincing direct evidence for an accretion disk in any AGN. Arp 102B appears to be a low-luminosity analog of 3C 390.3, and several lines of evidence point to the existence of small, hot ion tori illuminating an outer thin disk in both of these galaxies. The rarity of these emission-line profiles might be understood if this particular combination of ion torus/thin disk occurs only for a narrow range of ṁ(= Ṁ/ṀEdd).

scholarly journals The Kinematics of Quasar Broad Emission Line Regions Using a Disk-Wind Model

2017 ◽  
Vol 34 ◽  
Author(s):  
Suk Yee Yong ◽  
Rachel L. Webster ◽  
Anthea L. King ◽  
Nicholas F. Bate ◽  
Matthew J. O’Dowd ◽  
...  
Keyword(s):  
Emission Line ◽  
Line Profile ◽  
Inclination Angle ◽  
Opening Angle ◽  
Line Profiles ◽  
Wind Model ◽  
Disk Wind ◽  
Reverberation Mapping ◽  
Broad Emission ◽  
Line Region

AbstractThe structure and kinematics of the broad line region in quasars are still unknown. One popular model is the disk-wind model that offers a geometric unification of a quasar based on the viewing angle. We construct a simple kinematical disk-wind model with a narrow outflowing wind angle. The model is combined with radiative transfer in the Sobolev, or high velocity, limit. We examine how angle of viewing affects the observed characteristics of the emission line. The line profiles were found to exhibit distinct properties depending on the orientation, wind opening angle, and region of the wind where the emission arises.At low inclination angle (close to face-on), we find that the shape of the emission line is asymmetric, narrow, and significantly blueshifted. As the inclination angle increases (close to edge-on), the line profile becomes more symmetric, broader, and less blueshifted. Additionally, lines that arise close to the base of the disk wind, near the accretion disk, tend to be broad and symmetric. Single-peaked line profiles are recovered for the intermediate and equatorial wind. The model is also able to reproduce a faster response in either the red or blue sides of the line profile, consistent with reverberation mapping studies.

scholarly journals The effect of semantic relatedness on associative asymmetry in memory

2018 ◽  
Author(s):  
Vencislav Popov ◽  
Qiong Zhang ◽  
Griffin Koch ◽  
Regina Calloway ◽  
Marc N Coutanche
Keyword(s):  
Recall Test ◽  
Direct Evidence ◽  
Response Times ◽  
Semantic Relatedness ◽  
Cued Recall ◽  
Associative Symmetry ◽  
Single List ◽  
Symmetry Hypothesis ◽  
New Evidence ◽  
Holistic Representation

We provide new evidence concerning two opposing views of episodic associations: The independent associations hypothesis (IAH) posits that associations are unidirectional and separately modifiable links (A→B and A←B); the associative symmetry hypothesis (ASH), to the contrary, considers the association to be a holistic conjunction of A and B representations. While existing literature focuses on tests that compare the equality and correlation of forward and backward associations and favors ASH over IAH, we provide the first direct evidence of IAH by showing that forward and backward associations are separately modifiable for semantically related pairs. In two experiments, participants studied 30 semantically unrelated and 30 semantically related pairs intermixed in a single list, and then performed a series of up to eight cued-recall test cycles. All pairs were tested in each cycle, and the testing direction (A-? or B-?) alternated between cycles. Consistent with prior research, unrelated pairs exhibited associative symmetry – accuracy and response times improved gradually on each test, suggesting that testing in both directions strengthened the same association. In contrast, semantically related pairs exhibited a stair-like pattern, where performance did not change from odd to even tests when the test direction changed; it only improved between tests of the same direction. We conclude that episodic associations can have either a holistic representation (ASH) or separate directional representations (IAH), depending on the semantic relatedness of their constituent items.

Ca II Emission from Late-type Stars

1983 ◽  
Vol 5 (2) ◽  
pp. 152-157 ◽  
Author(s):  
L. E. Cram
Keyword(s):  
Line Profile ◽  
Strong Correlation ◽  
Velocity Fields ◽  
Line Profiles ◽  
Late Type ◽  
Wide Range ◽  
Cool Stars ◽  
Visual Magnitude ◽  
The Absolute ◽  
Emission Core

Two recent observational surveys of the Ca II resonance lines (Zarro and Rodgers 1983; Linsky et al. 1979) illustrate the great diversity of line profile shapes found in the spectra of cool stars. This diversity reflects a corresponding wide range in the underlying chromospheric properties of the stars. There are, however, three well-marked systematic trends in the shapes of Ca II line profiles which presumably reflect systematic trends in chromospheric properties. One of these, the Wilson-Bappu effect (Wilson and Bappu 1957), describes the strong correlation betweeen the width of the emission core (see Figure 1) and the absolute visual magnitude of the star. Despite much work, it is still not clear whether this is due primarily to systematic changes of velocity fields (e.g. Hoyle and Wilson 1958) or optical depths (e.g. Jefferies and Thomas 1959) in stellar chromospheres.

scholarly journals New Progress in Mode Detection and Identification in δ Scuti Stars by the Analysis of Line Profile Variations

2000 ◽  
Vol 176 ◽  
pp. 463-464
Author(s):  
L. Mantegazza ◽  
E. Poretti ◽  
M. Bossi ◽  
N. S. Nuñez ◽  
A. Sacchi ◽  
...  
Keyword(s):  
High Resolution ◽  
Line Profile ◽  
High Resolution Spectroscopy ◽  
Line Profiles ◽  
Powerful Technique ◽  
Mode Detection ◽  
Detection And Identification ◽  
Scuti Stars ◽  
Δ Scuti Stars ◽  
Nonradial Pulsation

Abstractδ Sct stars are among the most promising targets to perform ground-based asteroseismology. High resolution spectroscopy offers us a powerful technique to identify radial and nonradial pulsation modes, since we can easily detect oscillations and travelling features in the line profiles.

Problems in the Formation of Neutral Helium Lines in Early Type Stars

1970 ◽  
Vol 1 (7) ◽  
pp. 326-328
Author(s):  
R. W. Simpson
Keyword(s):  
Absorption Coefficient ◽  
Electron Scattering ◽  
Growth Analysis ◽  
Line Profiles ◽  
Early Type ◽  
Line Absorption ◽  
Early Type Stars ◽  
Made In ◽  
The Continuum

The aim of this work is to investigate certain assumptions that have been made in calculating line profiles and equivalent widths of neutral helium lines in early type stars. The effect of electron scattering on the continuum flux is investigated and a curve of growth analysis carried out to study this effect. The theories involved in calculating the line absorption coefficient are also investigated.

scholarly journals MOBSTER – III. HD 62658: a magnetic Bp star in an eclipsing binary with a non-magnetic ‘identical twin’

2019 ◽  
Vol 490 (3) ◽  
pp. 4154-4165 ◽  
Author(s):  
M E Shultz ◽  
C Johnston ◽  
J Labadie-Bartz ◽  
V Petit ◽  
A David-Uraz ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Light Curve ◽  
Line Profile ◽  
Longitudinal Magnetic Field ◽  
Stellar Structure ◽  
Line Profiles ◽  
Dipole Strength ◽  
Rotational Modulation ◽  
Brightness Modulation

ABSTRACT HD 62658 (B9p V) is a little-studied chemically peculiar star. Light curves obtained by the Kilodegree Extremely Little Telescope (KELT) and Transiting Exoplanet Survey Satellite (TESS) show clear eclipses with a period of about 4.75 d, as well as out-of-eclipse brightness modulation with the same 4.75 d period, consistent with synchronized rotational modulation of surface chemical spots. High-resolution ESPaDOnS circular spectropolarimetry shows a clear Zeeman signature in the line profile of the primary; there is no indication of a magnetic field in the secondary. PHOEBE modelling of the light curve and radial velocities indicates that the two components have almost identical masses of about 3 M⊙. The primary’s longitudinal magnetic field 〈Bz〉 varies between about +100 and −250 G, suggesting a surface magnetic dipole strength Bd = 850 G. Bayesian analysis of the Stokes V profiles indicates Bd = 650 G for the primary and Bd < 110 G for the secondary. The primary’s line profiles are highly variable, consistent with the hypothesis that the out-of-eclipse brightness modulation is a consequence of rotational modulation of that star’s chemical spots. We also detect a residual signal in the light curve after removal of the orbital and rotational modulations, which might be pulsational in origin; this could be consistent with the weak line profile variability of the secondary. This system represents an excellent opportunity to examine the consequences of magnetic fields for stellar structure via comparison of two stars that are essentially identical with the exception that one is magnetic. The existence of such a system furthermore suggests that purely environmental explanations for the origin of fossil magnetic fields are incomplete.

scholarly journals First Detection of a Frequency Multiplet in the Line Profile Variations of RR Lyrae: Towards an Understanding of the Blazhko Effect

2000 ◽  
Vol 176 ◽  
pp. 286-290 ◽  
Author(s):  
K. Kolenberg ◽  
C. Aerts ◽  
M. Chadid ◽  
D. Gillet
Keyword(s):  
Line Profile ◽  
Theoretical Models ◽  
Theoretical Modelling ◽  
Line Profiles ◽  
Multiplet Structure ◽  
Complete Understanding ◽  
Period Analysis ◽  
Essential Step ◽  
Rr Lyrae ◽  
Blazhko Effect

AbstractWe provide the first detection of a frequency multiplet in the line profile variations of RR Lyrae. Performing a period analysis on 669 high resolution line profiles obtained with the spectrograph ELODIE at OHP, we clearly detect a multiplet structure, with a separation equal to the Blazhko frequency, around the main frequency and its harmonics. The triplet components are very prominent; additional observations are needed to decide about the existence of a quintuplet. The complete understanding of the origin of the Blazhko effect still needs further theoretical modelling and better observations. Our detection of the frequency multiplet in the line profile variations is a first essential step towards a decisive confrontation between the theoretical models and the observations.

scholarly journals Measurement of line profiles

1986 ◽  
Vol 118 ◽  
pp. 401-412
Author(s):  
David F. Gray
Keyword(s):  
Spectral Line ◽  
High Precision ◽  
Line Profile ◽  
Line Profiles ◽  
Spectral Line Profile ◽  
The University

The basic requirements for high precision spectral line profile measurements are reviewed, with the observatory at the University of Western Ontario serving to illustrate several of the points.

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